A duplex mode of a radio communications system includes time division duplex (TDD, Time Division Duplex) and frequency division duplex (FDD, Frequency Division Duplex). On one TDD carrier, a UE cannot receive and send information at the same time, which means that either uplink transmission or downlink transmission is allowed at a given point of time. FDD systems may also be classified into full-duplex FDD and half-duplex FDD, both of which have a pair of carriers, namely, one uplink carrier and one downlink carrier. In the full-duplex FDD, a UE can separately receive and send information on the pair of uplink and downlink carriers at the same time; however, in the half-duplex FDD, a UE can only use a carrier of one direction at a given point of time, which means that either the downlink carrier or the uplink carrier is used.
In a radio communications system, a carrier aggregation technology may be used to improve a peak rate of a user equipment (UE, User Equipment), to be specific, multiple carriers may be configured together for one UE to use. The multiple carriers may be multiple FDD carriers or multiple TDD carriers, and if the multiple carriers are multiple TDD carriers, uplink-downlink configurations on the multiple TDD carriers are the same.
A dynamic TDD carrier technology may be introduced into an evolved radio communications system in the future. Specifically, in the existing TDD carrier technology, both uplink and downlink subframes on a TDD carrier are configured by using broadcast signaling, and switch between uplink and downlink subframes is slow or even does not occur at all. However, in the dynamic TDD carrier technology, directions of some or all subframes on a dynamic TDD carrier may be dynamically determined by a base station according to a service requirement of a UE, that is, one subframe may be dynamically changed to an uplink subframe or a downlink subframe. Apparently, the UE still cannot receive or send information at the same time.
A carrier aggregation technology in which uplink-downlink configurations of carriers are different may also be introduced into an evolved radio communications system in the future. Specifically, for example, two TDD carriers may be configured for a UE, and TDD uplink-downlink configurations of the two TDD carriers are different. In another example, one FDD carrier and one TDD carrier may be aggregated, and uplink-downlink configurations of the two carriers are also different. In this case, a conflicted subframe exists in some subframes, that is to say, the conflicted subframe is an uplink subframe on one TDD carrier, and the conflicted subframe is a downlink subframe on another TDD carrier at the same time. Therefore, in the conflicted subframe, a UE that does not support simultaneous transmission and reception on two carriers, namely, a half-duplex UE, either sends information in the conflicted subframe on one carrier or receives information in the conflicted subframe on another carrier.
The foregoing problem in which a half-duplex UE cannot perform simultaneous reception and transmission may occur in scenarios of the foregoing dynamic TDD carrier and aggregation of carriers with different uplink-downlink configurations, and compromises resource utilization. The present invention is directed at solving a problem about how to improve resource utilization by a half-duplex UE in the foregoing scenarios.